zangobot

Another day, another neural CTF to solve!
This challenge is pretty straight-forward: a keras model is given as only file of the challenge.
The first I thought was:

Ehi, it’s just another gradient descent! Let’s try it!… and I failed hard.
The network doesn’t compute anything, it just takes in input a greyscale 68 x 218 image and it outputs a number between 0 and 1.
Nothing special.
If you try to apply some gradient descent on the network, the result will be a useless image.

What to do now?
Having a look to a dump of the file containing the model was somehow enlighting: